#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>

int main() {
    int a;
    int ans = 0;
    while (scanf("%d", &a) != EOF) 
    {
        for (int i=1;i<=a-1;i++)
        {
            for (int j=1;j<=i+1;j++)
            {
                ans += j;
            }
        }
        printf("%d", ans);

    }
    return 0;
}